US8331491B2 - Signal derotating receiver - Google Patents
Signal derotating receiver Download PDFInfo
- Publication number
- US8331491B2 US8331491B2 US10/340,577 US34057703A US8331491B2 US 8331491 B2 US8331491 B2 US 8331491B2 US 34057703 A US34057703 A US 34057703A US 8331491 B2 US8331491 B2 US 8331491B2
- Authority
- US
- United States
- Prior art keywords
- phase
- signal
- received signal
- receiver
- signals
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related, expires
Links
Images
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N5/00—Details of television systems
- H04N5/14—Picture signal circuitry for video frequency region
- H04N5/21—Circuitry for suppressing or minimising disturbance, e.g. moiré or halo
- H04N5/211—Ghost signal cancellation
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
- H04L27/2655—Synchronisation arrangements
- H04L27/2662—Symbol synchronisation
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
- H04N21/40—Client devices specifically adapted for the reception of or interaction with content, e.g. set-top-box [STB]; Operations thereof
- H04N21/41—Structure of client; Structure of client peripherals
- H04N21/426—Internal components of the client ; Characteristics thereof
- H04N21/42607—Internal components of the client ; Characteristics thereof for processing the incoming bitstream
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
- H04N21/60—Network structure or processes for video distribution between server and client or between remote clients; Control signalling between clients, server and network components; Transmission of management data between server and client, e.g. sending from server to client commands for recording incoming content stream; Communication details between server and client
- H04N21/61—Network physical structure; Signal processing
- H04N21/6106—Network physical structure; Signal processing specially adapted to the downstream path of the transmission network
- H04N21/6112—Network physical structure; Signal processing specially adapted to the downstream path of the transmission network involving terrestrial transmission, e.g. DVB-T
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N5/00—Details of television systems
- H04N5/44—Receiver circuitry for the reception of television signals according to analogue transmission standards
- H04N5/455—Demodulation-circuits
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
- H04N21/40—Client devices specifically adapted for the reception of or interaction with content, e.g. set-top-box [STB]; Operations thereof
- H04N21/41—Structure of client; Structure of client peripherals
- H04N21/426—Internal components of the client ; Characteristics thereof
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
- H04N21/40—Client devices specifically adapted for the reception of or interaction with content, e.g. set-top-box [STB]; Operations thereof
- H04N21/43—Processing of content or additional data, e.g. demultiplexing additional data from a digital video stream; Elementary client operations, e.g. monitoring of home network or synchronising decoder's clock; Client middleware
- H04N21/438—Interfacing the downstream path of the transmission network originating from a server, e.g. retrieving MPEG packets from an IP network
- H04N21/4382—Demodulation or channel decoding, e.g. QPSK demodulation
Definitions
- This invention relates to a communication receiver.
- the European DVB-T Digital Video Broadcasting-Terrestrial
- DTT digital terrestrial television
- COFDM Coded Orthogonal Frequency Division Multiplexing
- the signals After reception in the television receiver, the signals are sampled, for example using a resampler, and are mixed down to baseband. The start of each active symbol is found, and then the active symbols are applied to a Fast Fourier Transform (FFT) processor, and subsequently to a channel estimator, to extract the wanted information.
- FFT Fast Fourier Transform
- the area close to the transmission path may include objects such as tall buildings, which cause echoes. That is, a signal may be received at a receiver twice, once on a direct path from the transmitter, and then, after a short delay, as an echo. Further, there may be no direct line of sight from the transmitter to the receiver, in which case the receiver will only receive echoes. The effect of this is that the first signal received may not necessarily have the strongest power. There will therefore be combinations of pre-echoes arriving before the strongest signal and echoes arriving afterwards.
- DVB-T COFDM signals include a cyclic prefix guard interval for each active symbol. Specifically, a portion of the active symbol is repeated before the next active symbol.
- a time domain correlation between samples which are an active window length apart yield large powers in the guard interval of the echo. These correlations can be used to correctly position the window when large echoes are present, although the technique is not as effective for smaller echoes. If the smaller echoes lag the larger ones, then correct positioning of the windowing relative to the first large echo (or relative to the main signal if no large pre-echo is present), will result in a good solution. On the other hand, if the smaller echo is a pre-echo, this may not be the case, as the pre-echo will be introducing ISI.
- One solution to this problem is to pull back the window position, calculated using the correlations in time, which can avoid ISI, but which rotates the signal in the frequency domain. Large rotations in the frequency domain can adversely affect the performance of the channel estimator. Moreover, the guard interval prefix must be removed before the signals are further processed. The initial position of the prefix can be found, and it is also preferable to allow correction for any changes in position caused by subsequent variations in sampling rate. Again such corrections have the effect of rotating the signal in the frequency domain.
- a receiver circuit which includes a derotator circuit, that is a circuit which can apply a rotation that is equal and opposite to that previously applied, before a signal is applied to a channel estimator.
- a method of processing received signals that includes applying a rotation which is equal and opposite to that previously applied, before the signal is applied to a channel estimator.
- the rotation that is applied can compensate for that previously applied, thereby improving channel estimation, and ultimately improving signal reception.
- FIG. 1 is a simplified block schematic diagram of a receiver circuit in accordance with the invention.
- FIG. 2 is an illustration of the operation of the derotator shown in the receiver circuit of FIG. 1 .
- FIG. 1 shows simplified block diagram of a receiver circuit or system in accordance with the present invention. It will be appreciated that many of the receiver functions can be carried out in a different order from that illustrated in FIG. 1 and as described below, and that FIG. 1 is exemplary only.
- the receiver includes an antenna (not shown) and a tuner (not shown) for receiving signals and downconverting the received signals to an intermediate frequency.
- the receiver further includes a further mixer stage 10 , for downconverting to baseband, and a resampler 12 , for obtaining digital samples of in-phase ( 1 ) and quadrature (Q) components of the signal.
- the sampler is controllable in the sense that its sampling position can be adjusted.
- Output signals from the resampler 12 are supplied to a processing device 14 that removes the cyclic components preceding each active symbol.
- the sampling position of the resampler 12 must be controlled such that the assumed position of the start of each symbol accurately coincides with the actual position in the received signal.
- This control of the sampling position is achieved by adjusting the phase of the resampler 12 under control of a resampler controller 16 . Such adjustments of the phase, in effect, rotate the signal in the phase plane.
- An algorithm to track the resampler displacement offset should in general not have large corrections in any particular symbol. However, it may be advantageous for it to be able to do so.
- the baseband I- and Q-data signals are supplied to a Fast Fourier Transform (FFT) processor 18 .
- FFT Fast Fourier Transform
- the FFT window may be pulled back in time. Again, this has the effect of rotating the spectrum of the main signal.
- the data signals are supplied to a derotator block 20 .
- FIG. 2 shows the values of the I- and Q-samples at one particular illustrative moment in time. Ignoring the effect of the rotation of the signal introduced by the resampler position correction algorithm and the Fast Fourier Transform processor window position pullback, the sample values would be at the position marked PI in FIG. 2 .
- the resampler position correction algorithm has altered the position of the signal by SP1 samples, and the Fast Fourier Transform processor window position has been pulled back by a further SP2 samples, which have introduced a rotation which means that, thereafter, the sample values are at the position marked P 2 (as shown in FIG. 2 ).
- the derotator 20 therefore detects the amount by which the Fast Fourier Transform processor window position has been pulled back, that is, SP2 samples.
- the derotator 20 also detects the size of the correction applied to the resampler position in each symbol, and hence the cumulative correction, that is, SP1 samples.
- the derotator 20 then forms the sum SP of SP1 and SP2, and calculates the total applied rotation ⁇ , as described above.
- a rotation of a complex value can be achieved by complex multiplication, and, in this case, an equal and opposite rotation is applied to compensate for that previously applied.
- the output data signal output by the derotator 20 is then input to a channel estimator 22 including an equalizer, demultiplexer and deinterleaver 24 and decoder 26 , which recover the originally transmitted bitstream, in a generally conventional way.
- the channel equalizer relies upon the channel being steady for multiple symbols. If a large resampler displacement offset is added, then the large phase ramp introduced will introduce an apparent rapid change in the channel and thus degrade the channel equalizer performance.
- the performance of the channel estimator can be optimized by removal in the derotator 20 of any previously applied rotation, thus improving the performance of the device. Specifically, the derotator can compensate for the introduced phase ramps, and therefore rapid movements in window position are possible, without degrading performance.
- the window position may advantageously be rotated either forwards or backwards.
- the invention has been described above in terms of a forwards rotation being compensated by a backwards derotation, it will be appreciated that the invention is equally applicable to compensating a backwards rotation of the window, by means of a forward rotation.
- the receiver system has been described herein with all of the components on a single device, such as a large scale integrated circuit. However, it will be appreciated that the different functions may be achieved in different devices, and in different ways from those described.
Abstract
Description
θ=2πn(SP/N)
S2=IS2+jQS2,
is obtained from the input sample position S1, having I- and Q-values IS1 and QS1, where:
S1=IS1+jQS1,
by means of the complex multiplication:
IS2+jQS2=(IS1+jQS1)e −jθ.
Claims (32)
Applications Claiming Priority (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB0017132.2 | 2000-07-12 | ||
GB0017132A GB2364866B (en) | 2000-07-12 | 2000-07-12 | Television receiver |
GBPCT/GB00/04001 | 2000-10-18 | ||
PCT/GB2000/004001 WO2002005550A1 (en) | 2000-07-12 | 2000-10-18 | Television receiver |
WOPCT/GB00/04001 | 2000-10-18 |
Publications (2)
Publication Number | Publication Date |
---|---|
US20040028161A1 US20040028161A1 (en) | 2004-02-12 |
US8331491B2 true US8331491B2 (en) | 2012-12-11 |
Family
ID=9895535
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US10/340,577 Expired - Fee Related US8331491B2 (en) | 2000-07-12 | 2003-01-10 | Signal derotating receiver |
Country Status (5)
Country | Link |
---|---|
US (1) | US8331491B2 (en) |
EP (1) | EP1302067B1 (en) |
AT (1) | ATE516663T1 (en) |
GB (1) | GB2364866B (en) |
WO (1) | WO2002005550A1 (en) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN103888387A (en) * | 2012-12-20 | 2014-06-25 | 中山大学深圳研究院 | Rotation signal receiver |
Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH1075228A (en) | 1996-08-30 | 1998-03-17 | Jisedai Digital Television Hoso Syst Kenkyusho:Kk | Ofdm demodulator |
EP0933903A2 (en) | 1998-01-30 | 1999-08-04 | Advanced Digital Television Broadcasting Laboratory | Suppression of phase noise in multicarrier reception |
WO2000021228A1 (en) | 1998-10-02 | 2000-04-13 | Usa Digital Radio, Inc. | Method for equalization of complementary carriers in an am compatible digital audio broadcast system |
EP1005205A2 (en) | 1998-11-25 | 2000-05-31 | Lucent Technologies Inc. | Fast start-up for multicarrier systems |
EP1049301A2 (en) | 1999-03-31 | 2000-11-02 | Texas Instruments Incorporated | Sampling clock correction in a multicarrier receiver |
US6233276B1 (en) * | 1999-09-13 | 2001-05-15 | Virata Corporation | XDSL modem having time domain filter for ISI mitigation |
US6456654B1 (en) * | 1998-12-22 | 2002-09-24 | Nortel Networks Limited | Frame alignment and time domain equalization for communications systems using multicarrier modulation |
US6704374B1 (en) * | 2000-02-16 | 2004-03-09 | Thomson Licensing S.A. | Local oscillator frequency correction in an orthogonal frequency division multiplexing system |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2000269919A (en) * | 1999-03-16 | 2000-09-29 | Matsushita Electric Ind Co Ltd | Ofdm communication unit |
US6891792B1 (en) * | 1999-05-14 | 2005-05-10 | At&T Corp. | Method for estimating time and frequency offset in an OFDM system |
GB2373693B (en) * | 1999-08-27 | 2003-01-15 | Mitsubishi Electric Inf Tech | OFDM frame synchronisation |
JP3492565B2 (en) * | 1999-09-13 | 2004-02-03 | 松下電器産業株式会社 | OFDM communication device and detection method |
US7272175B2 (en) * | 2001-08-16 | 2007-09-18 | Dsp Group Inc. | Digital phase locked loop |
US7453792B2 (en) * | 2002-11-14 | 2008-11-18 | Edgewater Computer Systems, Inc. | Receiver architecture for pilot based OFDM systems |
-
2000
- 2000-07-12 GB GB0017132A patent/GB2364866B/en not_active Expired - Fee Related
- 2000-10-18 WO PCT/GB2000/004001 patent/WO2002005550A1/en active Application Filing
- 2000-10-18 EP EP00969677A patent/EP1302067B1/en not_active Expired - Lifetime
- 2000-10-18 AT AT00969677T patent/ATE516663T1/en not_active IP Right Cessation
-
2003
- 2003-01-10 US US10/340,577 patent/US8331491B2/en not_active Expired - Fee Related
Patent Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH1075228A (en) | 1996-08-30 | 1998-03-17 | Jisedai Digital Television Hoso Syst Kenkyusho:Kk | Ofdm demodulator |
EP0933903A2 (en) | 1998-01-30 | 1999-08-04 | Advanced Digital Television Broadcasting Laboratory | Suppression of phase noise in multicarrier reception |
WO2000021228A1 (en) | 1998-10-02 | 2000-04-13 | Usa Digital Radio, Inc. | Method for equalization of complementary carriers in an am compatible digital audio broadcast system |
EP1005205A2 (en) | 1998-11-25 | 2000-05-31 | Lucent Technologies Inc. | Fast start-up for multicarrier systems |
US6456654B1 (en) * | 1998-12-22 | 2002-09-24 | Nortel Networks Limited | Frame alignment and time domain equalization for communications systems using multicarrier modulation |
EP1049301A2 (en) | 1999-03-31 | 2000-11-02 | Texas Instruments Incorporated | Sampling clock correction in a multicarrier receiver |
US6233276B1 (en) * | 1999-09-13 | 2001-05-15 | Virata Corporation | XDSL modem having time domain filter for ISI mitigation |
US6704374B1 (en) * | 2000-02-16 | 2004-03-09 | Thomson Licensing S.A. | Local oscillator frequency correction in an orthogonal frequency division multiplexing system |
Non-Patent Citations (1)
Title |
---|
Mignone, Vittoria et al., "CD3-OFDM: A Novel Demodulation Scheme for Fixed and Mobile Receivers", IEEE Transactions on Communications, Sep. 1996, pp. 1144-1151, vol. 44, No. 9. |
Also Published As
Publication number | Publication date |
---|---|
ATE516663T1 (en) | 2011-07-15 |
GB0017132D0 (en) | 2000-08-30 |
EP1302067B1 (en) | 2011-07-13 |
GB2364866A (en) | 2002-02-06 |
GB2364866B (en) | 2004-05-19 |
US20040028161A1 (en) | 2004-02-12 |
WO2002005550A1 (en) | 2002-01-17 |
EP1302067A1 (en) | 2003-04-16 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US7362802B2 (en) | Frequency domain equalizer for wireless commuications system | |
EP2253113B1 (en) | Detection of a dvb-t2 preamble having frequency-shifted prefix and suffix | |
JPH11503895A (en) | Method and apparatus for estimating frequency offset and timing of a multi-carrier modulation system | |
US20040146123A1 (en) | Equalization in orthogonal frequency domain multiplexing | |
WO2009122727A1 (en) | Receiver, method of reception, reception program, integrated circuit, and digital television | |
US7379514B2 (en) | Phase advance compensation for MIMO time-switch preamble modes | |
US6240146B1 (en) | Demodulating digital video broadcast signals | |
KR100930988B1 (en) | A phase tracking system and method | |
US6950483B2 (en) | Timing misalignment estimation | |
US7551691B2 (en) | Receiver for a multi-carrier communication system | |
JP4465797B2 (en) | Receiving apparatus and receiving method | |
US20060039507A1 (en) | Method and apparatus for estimating SFO in digital receiver, and method and apparatus for compensating for sampling frequency using the estimated SFO in the digital receiver | |
US20020137510A1 (en) | Method and system for adaptive equalization for receivers in a wide-band satellite communications system | |
US8331491B2 (en) | Signal derotating receiver | |
US7324599B2 (en) | Frequency correction for a multicarrier system | |
US20050141660A1 (en) | Symbol timing recovery and broadcast receiver using the same | |
JP2002026861A (en) | Demodulator and demodulation method | |
KR100587279B1 (en) | apparatus and method for correcting timing in digital broadcasting receiver | |
Gallardo et al. | Performance of DVB-T OFDM based single frequency networks: effects of frame synchronisation, carrier frequency offset and non-synchronised sampling errors | |
KR100290855B1 (en) | Appartus for equarizing of digital broadcasting receiver | |
KR100697526B1 (en) | Tracking device for digital broadcast receiver | |
JPH10322305A (en) | Demodulator for quadrature frequency division multiplex system | |
JP5543033B2 (en) | Receiving apparatus and receiving method | |
CN103888387A (en) | Rotation signal receiver | |
Ho et al. | OFDM synchronization scheme to be used on a non frequency selective satellite channel |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: CONEXANT SYSTEMS, INC., CALIFORNIA Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:VICKERS, MARTIN;REEL/FRAME:018335/0249 Effective date: 20030724 |
|
AS | Assignment |
Owner name: BANK OF NEW YORK TRUST COMPANY, N.A., THE,ILLINOIS Free format text: SECURITY AGREEMENT;ASSIGNOR:BROOKTREE BROADBAND HOLDING, INC.;REEL/FRAME:018573/0337 Effective date: 20061113 Owner name: BANK OF NEW YORK TRUST COMPANY, N.A., THE, ILLINOI Free format text: SECURITY AGREEMENT;ASSIGNOR:BROOKTREE BROADBAND HOLDING, INC.;REEL/FRAME:018573/0337 Effective date: 20061113 |
|
AS | Assignment |
Owner name: BANK OF NEW YORK TRUST COMPANY, N.A.,ILLINOIS Free format text: SECURITY AGREEMENT;ASSIGNOR:CONEXANT SYSTEMS, INC.;REEL/FRAME:018711/0818 Effective date: 20061113 Owner name: BANK OF NEW YORK TRUST COMPANY, N.A., ILLINOIS Free format text: SECURITY AGREEMENT;ASSIGNOR:CONEXANT SYSTEMS, INC.;REEL/FRAME:018711/0818 Effective date: 20061113 |
|
AS | Assignment |
Owner name: CONEXANT SYSTEMS, INC., CALIFORNIA Free format text: RELEASE BY SECURED PARTY;ASSIGNOR:BANK OF NEW YORK MELLON TRUST COMPANY, N.A. (FORMERLY, BANK OF NEW YORK TRUST COMPANY, N.A.);REEL/FRAME:021523/0790 Effective date: 20080808 Owner name: CONEXANT SYSTEMS, INC., CALIFORNIA Free format text: RELEASE BY SECURED PARTY;ASSIGNOR:BANK OF NEW YORK MELLON TRUST COMPANY, N.A. (FORMERLY, BANK OF NEW YORK TRUST COMPANY, N.A.);REEL/FRAME:021523/0804 Effective date: 20080808 Owner name: CONEXANT SYSTEMS, INC.,CALIFORNIA Free format text: RELEASE BY SECURED PARTY;ASSIGNOR:BANK OF NEW YORK MELLON TRUST COMPANY, N.A. (FORMERLY, BANK OF NEW YORK TRUST COMPANY, N.A.);REEL/FRAME:021523/0804 Effective date: 20080808 |
|
AS | Assignment |
Owner name: NXP, B.V., NETHERLANDS Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:CONEXANT SYSTEMS, INC.;REEL/FRAME:021531/0523 Effective date: 20080808 Owner name: NXP, B.V.,NETHERLANDS Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:CONEXANT SYSTEMS, INC.;REEL/FRAME:021531/0523 Effective date: 20080808 |
|
AS | Assignment |
Owner name: TRIDENT MICROSYSTEMS (FAR EAST) LTD.,CAYMAN ISLAND Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:TRIDENT MICROSYSTEMS (EUROPE) B.V.;NXP HOLDING 1 B.V.;REEL/FRAME:023928/0552 Effective date: 20100208 Owner name: NXP HOLDING 1 B.V.,NETHERLANDS Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:NXP;REEL/FRAME:023928/0489 Effective date: 20100207 Owner name: NXP HOLDING 1 B.V., NETHERLANDS Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:NXP;REEL/FRAME:023928/0489 Effective date: 20100207 Owner name: TRIDENT MICROSYSTEMS (FAR EAST) LTD., CAYMAN ISLAN Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:TRIDENT MICROSYSTEMS (EUROPE) B.V.;NXP HOLDING 1 B.V.;REEL/FRAME:023928/0552 Effective date: 20100208 |
|
AS | Assignment |
Owner name: ENTROPIC COMMUNICATIONS, INC., CALIFORNIA Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:TRIDENT MICROSYSTEMS, INC.;TRIDENT MICROSYSTEMS (FAR EAST) LTD.;REEL/FRAME:028146/0178 Effective date: 20120411 |
|
REMI | Maintenance fee reminder mailed | ||
LAPS | Lapse for failure to pay maintenance fees | ||
STCH | Information on status: patent discontinuation |
Free format text: PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362 |
|
FP | Lapsed due to failure to pay maintenance fee |
Effective date: 20161211 |